Patent GB-390546-A (GB)
Title: Improvements in or relating to electrical signalling systems
IPC: H04M11/02
Filed: 1931-10-13
Abstract: 390,546. Automatic exchange systems. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, Liverpool. Oct. 13, 1931, No. 28473. Convention date, Oct. 13, 1930. [Class 40 (iv).] For displaying departmental information at a central point, say of a factory, a subscriber of a private exchange, by dialling a fixed number, gets access to special registering apparatus, and then by dialling a digit representing his own substation, gets access to an individual register which he sets by three further digits to control a lamp indicator. The indications from different substations are displayed in turn for a predetermined time on a common panel, the registers remaining in their set positions until a further indication is about to be recorded. If desired, signals can be redisplayed on the panel and an indication is given of the register set on which the displayed signal is stored. Setting of register. The subscriber A, to whom register group 1 is individual, dials the number necessary to extend his line over lineswitch C and selector D to the relay apparatus shown in Fig. 1. Relays 6 and 9 operate. As register group 1 is required, the subscriber dials 1, the impulse is repeated by 6 to magnet 25, and RS makes one step. When relay 12, which is energized in parallel with 25, releases at the end of the train, switching relay 20 energizes and locks over off-normal springs 28<1>, and when 18, which pulled up when 12 operated, releases, a circuit is completed for 15 and 19 in parallel. Relay 19 is differential and acts as a buzzer to return dial tone to the caller. The three digits of the signal are then transmitted and are repeated by 6 over 27 to operate magnets 48, 50, 52 in turn, which step HS, TS and US respectively. Relays 34 and 37 operate and hold during, each train and, as each train finishes, complete the circuit of magnet 40 which moves the distributer switch SS one step. Relay 12 energizes in the impulsing circuit but, as 15 is energized and 20 is locked, its operation is without effect. When the third train is completed SS moves to position 4, the operating earth in this instance being extended over 43 and 73 to energize 62 which locks to 32. When the units switch US moves off normal the green lamp 1 is illuminated. The caller replaces his receiver, relays 6 and 9 de-energize and release magnet 26 pulls up to release RS. When this switch regains its normal position springs 28<1> open and 20 falls away, whereupon 15 and 19 de-energize and the circuit of 26 is broken. Display of signal. When relay 62 energized, earth on conductor 67 was replaced by battery and earth was extended over 71 and wiper 100 of DTS to energize relay 86. Relay 86 completes a series circuit for relay 81 and magnet 77 of switch DS. As register group 1 has been marked, battery on 67 is extended over 80 and relay 81 only is operated. Had any other contact been marked earth would have been extended over 80 to short 81 and 77 would have stepped DS until the marked terminal had been reached, when 81 would have pulled up. Relay 81 connects ground over 79 to energize 72 which completes circuits over HS, TS and US for the display lamps and illuminates No. 1 Red lamp to indicate that the information on register group No. 1 is being displayed. Relay 81 also connects earth to the chain of slow energizing relays 93, 94, 95 which pull up in turn, and then release, relay 95 completing, each time it pulls up,'a circuit over 102 for magnet 98 which steps DTS. Alarm AS is operated. When DTS moves into its fifth position a circuit is completed over 101, 80 and 67 which shorts 62 and this relay releases. 72 falls away and removes the display. The release of 62 replaces earth on 69 which shorts down start relay 86 ; DTS steps to normal over off-normals 103 and 81 deenergizes. Should another register group be waiting to display, 86 is again energized over 100 and 71 and DS hunts for the marked egister group and the operation is repeated. A signal can be recalled by the operation of the relative key REG1, REG2, &c., which energizes 91 and 72 in series. The display is maintained as long as the key is depressed and the automatic display of new signals is suspended as the start circuit is opened by 91. The operation of a display key has no effect whilst the indicator is in use as the circuit through the keys is broken at operated contacts of 86. Resetting of register group. Should the operator at station A have a further signal to display, the register group No. 1 is seized as before described. When relay 20 energizes on the release of 12, wiper 28 extends earth from off-normal contacts 34, 55, 57 and 59 to maintain 18 energized. Relay 31 pulls up in this circuit and closes circuits for release magnets 41, 49, 51 and 53. When all the registers have restored 31 and 18 release and 15 and 19 pull up to'allow dial tone to be returned to the caller. The registers are reset as described above. The registers can be released by the operation of release keys 1, 2, 3, &c.